The primary objective of this research program is to study the phenomena involved in immunoglobulin gene expression and to develop an understanding towards the control mechnisms that regulate this gene expression. In the past year, we have studied the idiotypic specificities of the anti-VHa2 allotype antibodies, and have reason to believe that these idiotypic specificities are involved in the regulation of the expression of the a2 allotype. We have found that the anti-VHa2 allotype antibodies from different rabbits have a common idiotype. Furthermore, we found antibodies to this common idiotype can stimulate the synthesis of the a2 allotype in alpha 1 alpha 2 heterozygous rabbits. In the following year, I propose to do the following studies: 1) to continue the studies concerning the antibodies to the other VH alpha locus allotypes (i.e., a1 and a3) and determine if they also have a common idiotype; 2) to study the idiotypic specificities of the antibodies to the light chain and to the constant region heavy chain allotypes; 3) to study the effect of the antibody to the common idiotype of the anti-VHa2 allotype antibodies, whether it can inhibit the synthesis of this common idiotype in rabbits (i.e., commonly called "idiotype suppression" ; 4) to study the effect(s) of antibodies to the common idiotype of the anti-VHa2 allotype antibodies on the expression of the a2 allotype. Our preliminary data indicate that the anti-common idiotype antibodies to the anti-VHa2 allotype antibodies can enhance the synthesis of the a2 allotype. However, these effects were transient and incomplete. We will continue to search for possible ways to make these effects more complete and long-lasting.